Scientists have discovered a potential cure for a deadly fungal disease that is devastating amphibian populations worldwide.

The Critically Endangered Morelet’s tree frog, just one of many amphibian species at risk from chytridiomycosis.

Deadly disease

Chytridiomycosis, a deadly disease caused by the ‘chytrid’ fungus, Batrachochytrium dendrobatidis, has been linked to many amphibian declines around the world. It is also thought to be at least partly responsible for a number of amphibian extinctions.

Until recently, scientists have struggled to discover an effective means of controlling the spread of this devastating disease.

However, in a new study published in the journal Biodiversity and Conservation, researchers from Oregon State University report that a species of zooplankton – a tiny aquatic animal – has been found to eat the fungus.

Daphnia magna, a type of ‘water flea’, consumes the aquatic, free-swimming spores which form the infective stage of the chytrid fungus. This observation has raised the possibility of using biological control – a method of controlling pest species using natural predators or parasites – to fight chytridiomycosis.

Chytridiomycosis is believed to have contributed to the extinction of the golden toad in Costa Rica.

Biological control

Scientists are unsure what is causing the rapid spread of the chytrid fungus, and efforts to eradicate it from localised areas have so far been unsuccessful. Control measures to reduce the impacts of the disease on amphibian populations may be a more realistic option.

According to Julia Buck, the lead author of the study, “We feel that biological control offers the best chance to control this fungal disease, and now we have a good candidate for that.”

“Efforts to eradicate this disease have been unsuccessful, but so far no one has attempted biocontrol of the chytrid fungus. That may be the way to go.”

The southern gastric-brooding frog, an Australian species believed to have become extinct in 1981, possibly due in part to fungal disease.

The chytrid fungus is not always deadly at low levels, and the researchers suggest that using the zooplankton could reduce the density of the fungus enough to give amphibians a better chance of fighting off infection.

The scientists now need to conduct field studies to test how effective Daphnia magna may be at controlling the chytrid fungus in natural settings. This tiny organism inhabits amphibian breeding sites where chytrid transmission occurs, and may therefore be a useful tool in halting the unprecedented declines in the world’s amphibian species.

The Critically Endangered golden arrow poison frog, another species threatened by chytridiomycosis.